Let's break down the benchmark and explain what's being tested, compared, and what the pros and cons of each approach are.

Overview

MeasureThat.net is a platform for creating and running JavaScript microbenchmarks. The provided JSON represents a simple benchmark with two test cases: "cached Intl.NumberFormat" and "toLocaleString". The benchmark measures the performance of these methods in different browsers and devices.

Benchmark Definition JSON

The Benchmark Definition JSON contains basic information about the benchmark, such as its name, description, script preparation code, and HTML preparation code. In this case, both fields are empty, indicating that no specific script or HTML is required for the benchmark to run.

Individual Test Cases

Each test case represents a specific scenario being measured. Let's analyze them:

1. "cached Intl.NumberFormat"`
   • Benchmark Definition: window.a = window.a || new Intl.NumberFormat("en-US");\r\nvar a = window.a.format("10000")
   • This code creates a cached instance of the Internationalized Number Format (Intl.NumberFormat) for English (US) locale. The format method is then called on this instance with the string "10000". The benchmark measures how fast this code executes.
2. "toLocaleString"`
   • Benchmark Definition: var a = Number.parseFloat("10000.23").toFixed(2).toLocaleString("en-US")
   • This code converts a decimal number to a string using Number.parseFloat, rounds it to two decimal places with toFixed(2), and then formats the result as a localized string using toLocaleString for English (US) locale. The benchmark measures how fast this code executes.

Comparison

The comparison between these two methods is based on their execution speed. In general, the first method (cached Intl.NumberFormat) might be faster because it:

• Uses a cached instance of the formatting function
• Avoids the overhead of parsing a decimal number and converting it to an integer

On the other hand, the second method (toLocaleString) might be slower because:

• It involves additional steps (parsing, rounding, and formatting)
• The toLocaleString method might need to perform more operations on the locale-specific data

Pros and Cons

Here are some pros and cons of each approach:

1. Cached Intl.NumberFormat
   • Pros:
     • Reduces parsing overhead
     • Reuses the cached instance for multiple calls
   • Cons:
     • Requires setting up a cache (not present in this benchmark)
2. toLocaleString
   • Pros:
     • Handles locale-specific formatting more efficiently
     • May be more efficient if using a complex locale or formatting options
   • Cons:
     • Involves additional parsing and formatting steps

Library and Special JS Feature

In this benchmark, the Intl.NumberFormat library is used to handle internationalized number formatting. This library provides a standardized way to format numbers according to the rules of different locales.

There are no special JavaScript features or syntaxes being tested in these benchmarks.

Alternatives

If you wanted to modify or extend these benchmarks, here are some alternatives:

1. Use a different locale: Try changing the en-US locale in the benchmark definitions to test with other cultures.
2. Add more formatting options: Experiment with various formatting options for Intl.NumberFormat, such as minimumFractionDigits or maximumFractionDigits.
3. Compare with V8's built-in formatting functions: Measure the performance of JavaScript's built-in number formatting functions (e.g., toString(), toLocaleString()) against Intl.NumberFormat.
4. Incorporate other number formatting libraries: Compare the performance of different number formatting libraries, such as moment.js or date-fns.

Keep in mind that these alternatives may require modifications to the benchmark JSON and code.